/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.http.codec.support;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.function.Supplier;

import org.springframework.core.codec.Decoder;
import org.springframework.core.codec.Encoder;
import org.springframework.http.codec.ClientCodecConfigurer;
import org.springframework.http.codec.EncoderHttpMessageWriter;
import org.springframework.http.codec.FormHttpMessageWriter;
import org.springframework.http.codec.HttpMessageReader;
import org.springframework.http.codec.HttpMessageWriter;
import org.springframework.http.codec.ServerSentEventHttpMessageReader;
import org.springframework.http.codec.multipart.MultipartHttpMessageWriter;
import org.springframework.lang.Nullable;

/**
 * Default implementation of {@link ClientCodecConfigurer.ClientDefaultCodecs}.
 *
 * @author Rossen Stoyanchev
 */
class ClientDefaultCodecsImpl extends BaseDefaultCodecs implements ClientCodecConfigurer.ClientDefaultCodecs {

    @Nullable
    private DefaultMultipartCodecs multipartCodecs;

    @Nullable
    private Decoder<?> sseDecoder;

    @Nullable
    private Supplier<List<HttpMessageWriter<?>>> partWritersSupplier;


    /**
     * Set a supplier for part writers to use when
     * {@link #multipartCodecs()} are not explicitly configured.
     * That's the same set of writers as for general except for the multipart
     * writer itself.
     */
    void setPartWritersSupplier(Supplier<List<HttpMessageWriter<?>>> supplier) {
        this.partWritersSupplier = supplier;
    }


    @Override
    public ClientCodecConfigurer.MultipartCodecs multipartCodecs() {
        if (this.multipartCodecs == null) {
            this.multipartCodecs = new DefaultMultipartCodecs();
        }
        return this.multipartCodecs;
    }

    @Override
    public void serverSentEventDecoder(Decoder<?> decoder) {
        this.sseDecoder = decoder;
    }


    @Override
    protected void extendObjectReaders(List<HttpMessageReader<?>> objectReaders) {
        objectReaders.add(new ServerSentEventHttpMessageReader(getSseDecoder()));
    }

    @Nullable
    private Decoder<?> getSseDecoder() {
        return (this.sseDecoder != null ? this.sseDecoder : jackson2Present ? getJackson2JsonDecoder() : null);
    }

    @Override
    protected void extendTypedWriters(List<HttpMessageWriter<?>> typedWriters) {

        FormHttpMessageWriter formWriter = new FormHttpMessageWriter();
        formWriter.setEnableLoggingRequestDetails(isEnableLoggingRequestDetails());

        MultipartHttpMessageWriter multipartWriter = new MultipartHttpMessageWriter(getPartWriters(), formWriter);
        multipartWriter.setEnableLoggingRequestDetails(isEnableLoggingRequestDetails());

        typedWriters.add(multipartWriter);
    }

    private List<HttpMessageWriter<?>> getPartWriters() {
        if (this.multipartCodecs != null) {
            return this.multipartCodecs.getWriters();
        } else if (this.partWritersSupplier != null) {
            return this.partWritersSupplier.get();
        } else {
            return Collections.emptyList();
        }
    }


    /**
     * Default implementation of {@link ClientCodecConfigurer.MultipartCodecs}.
     */
    private static class DefaultMultipartCodecs implements ClientCodecConfigurer.MultipartCodecs {

        private final List<HttpMessageWriter<?>> writers = new ArrayList<>();

        @Override
        public ClientCodecConfigurer.MultipartCodecs encoder(Encoder<?> encoder) {
            writer(new EncoderHttpMessageWriter<>(encoder));
            return this;
        }

        @Override
        public ClientCodecConfigurer.MultipartCodecs writer(HttpMessageWriter<?> writer) {
            this.writers.add(writer);
            return this;
        }

        List<HttpMessageWriter<?>> getWriters() {
            return this.writers;
        }
    }

}
